This invention relates to the domain of level determination instruments. The invention more particularly relates to a modular laser type level determination system.
In general, level determination instruments are used in construction, for example for the construction of a horizontal surface fixed on columns or sidewalls, for levelling ground or for making measurements by a surveyor.
Instruments according to prior art, e.g., as disclosed in U.S. Pat. No. 6,014,211, usually comprise a housing with a base in which a laser source is installed that sends an upwards vertical beam towards a rotating pentaprism, e.g., pentaprism 20 of the ""211 patent. The rotating pentaprism then redirects the vertical beam at an angle equal to approximately 90xc2x0 to scan a horizontal light levelling plane. Under some conditions, these instruments cannot be placed horizontal and they are then arranged on inclined planes. To solve this defect, levels have been added to compensate for this type of inclination.
The prior art of U.S. Pat. No. 6,014,211 discloses a device generating a laser levelling plane. The device of the ""211 patent includes a housing containing a horizontal laser beam generator and a mirror placed in a vertical tube, installed on tope of a rotating motor assembly that rotates a pentaprism. With this type of device, it is impossible to make a fine adjustment of the orientation of the various elements such as the motor, the laser beam generator, the tube carrying the laser beam, these elements are relatively dispersed. The reliability of this device is significantly reduced because there is no integration between the different components. Furthermore, this type of device with a wire suspended pendulum may not be sufficiently robust to resist difficult conditions on site.
Therefore, the purpose of this invention is to overcome one or several of the disadvantages of prior art by defining a high precision and reliable modular laser type level determination system that integrates the motor driven module and levelling elements and the laser source in the same housing.
This objective is achieved by means of a modular laser level determination system comprising a laser beam generator in a housing, fixed with means of positioning with respect to a plane parallel to the plane of the base of the said housing, the laser beam being oriented towards a central shaft inside the housing not closed off by any obstacles and firstly passing through collimation means, a rotation drive module of an optical assembly comprising at least one reflection plane, the said rotation drive module being arranged along a direction approximately coaxial with the centre line of the laser beam, characterized by the fact that the rotation drive module of the said optical assembly comprises a brushless electronic switching motor with a hollow shaft, the stator of which is fitted to an element fixed in rotation about an axis parallel to the axis of the laser beam and that can be tilted by a module for determination and adjustment of the inclination with respect to a reference plane parallel to the support plane of the enclosure of the housing, the said laser beam generator being fixed to the brushless motor.
According to another feature of the invention, the said brushless motor comprises a wound stator, a rotor with a permanent magnet and an optical encoder connected to the rotor through the hollow shaft of the motor, the said optical incremental encoder associated with electronic means for detection of the rotor position being used to determine the precise position of the rotor, the position of the laser beam and to check rotation or oscillations between two motor positions.
According to another feature of the invention, the said electronic means for detection of the rotor position comprise at least one encoder position detection and motor control electronic card.
According to another feature of the invention, the said inclination determination and adjustment module comprises manual means of adjusting the inclination of the said element fixed in rotation.
According to another feature, the said inclination determination and adjustment module comprises a device with at least two mechanisms for levelling the said element fixed in rotation, these levelling mechanisms including particularly a micro-motor used to fix at least one screw screwed along a vertical axis of the housing.
According to another feature, the said inclination determination and adjustment module comprises a device with two jacks fixed to two corners of the said element fixed in rotation and the said rotation drive module, the two jacks being used to make a relative displacement of the axis of inclination of the said rotation drive module with respect to the vertical axis of the housing.
According to another feature, the said jacks are electric, these jacks being controlled through at least one electronic control card.
According to another feature, two levels perpendicular to each other and located in a plane parallel to the plane of the base on which the mounting base of the housing is supported are incorporated in a body including the laser beam generator, the direction of the laser beam being oriented with respect to the said base plane, these two levels detecting the relative position of the laser beam generator with respect to a reference plane.
According to another feature, a third xe2x80x9cverticalxe2x80x9d level perpendicular to the other two levels is built into the body that includes the laser beam generator to detect the relative position of the laser beam generator with respect to a reference plane.
According to another feature, the levels built into the laser beam generator are electronic level vials with optical reading, the optical reading being made using at least one electronic card.
According to another feature, the said inclination determination and adjustment module of the element fixed in rotation comprises a printed circuit, photodetectors and actuator means to determine the inclination of this module with respect to the mounting base of the housing.
According to another feature, the said rotating optical assembly comprises a rotating pentaprism, the laser beam generator equipped with a laser diode being aligned with the said hollow shaft and the said pentaprism along an axis depending on the verticality of the housing, the said pentaprism being oriented to reflect the laser beam by an angle of approximately 90xc2x0.
According to another feature, the said positioning means with respect to a plane parallel to the mounting base plane of the said housing comprise at least one manually adjustable screwing element.
According to another feature, the said positioning means with respect to a plane parallel to the mounting base plane of the said housing comprise at least one electric jack.
According to another feature, the system according to the invention comprises a double slope device, each slope being formed particularly by two plates, at least one of these plates being mobile and articulated through at least two balls, the two balls forming a generating line of a plane and being acted upon along another generating line of this plane by an elastic means towards a return position and in the other direction by electromagnetic equipment for adjusting the slope.
According to another feature, one of the plates in the double slope device is common to the two slopes.
According to another feature, the mobile plates of the double slope device are installed free to pivot about the said two balls, the rotation axes of the mobile plates being oriented perpendicular to each other.
According to another feature, the said electromechanical equipment comprises at least two stepping motors managed by electronic control means taking account of representative values of rotation angles of the mobile plates input by the user on an interface and at least one correction table.
According to another feature, the system according to the invention comprises a single slope device positioned between the said brushless motor (5) and the location of the levels (30, 31).
According to another feature, the housing comprises gripping means and a recess for use by a battery closed by a removable cover, a console with a display screen and control buttons being associated with the said housing particularly to control the said inclination determination and adjustment module and the encoder position detection and motor control electronic card.
The invention and its features and advantages will be more clearly understood after reading the description made with reference to the appended drawings given as non-limitative examples.